Add a lua script to clean the aliases file

Note that cmder doesn't ship with lua. Next step is converting this
script to perl, which ships with msysgit.

bin/alias.bat

@@ -15,6 +15,7 @@ if not ["%_temp%"] == ["%_temp2%"] (
 
 echo %* >> "%CMDER_ROOT%\config\aliases"
 doskey /macrofile="%CMDER_ROOT%\config\aliases"
+lua "%CMDER_ROOT%\scripts\clean_aliases.lua"
 echo Alias created
 endlocal
 goto:eof